DESCRIPTION: This proposed in vivo study will examine the possible problems associated with deteriorating (staining) margins of composite resin restorations. The specific aims of the study are to: 1) closely observe and morphologically characterize the margins of restorations which are undergoing staining; and 2) randomize those restorations into a treatment group (those that would have the stain removed and margin repaired) and a control group (those that would be observed periodically but not treated) for a three year follow up. The proposal outlines two separate clinical studies. One is a pilot study in which a network of 10 private practices would collect data (same as the clinical trial) on 300 patients and observe the stained resin margins for two years. This pilot project would be a basis for future extension of the project. The second clinical study is the primary clinical trial using the facilities and 380 patients at the University of Michigan School of Dentistry. Subjects in the randomized, partially blinded clinical trial will be assigned to treatment (preventive resin/sealant repair) or observation groups and recalled annually for three years. The primary dependent variable is the presence of recurrent caries over the three year period. Predictor variables include: morphological characteristics of the stained margin (direct assessmen and 15x magnified visual image); ordinal ratings for margin discoloration and adaptation; and localized bacteriologic assay for Streptococcus mutans. This study will test the validity of a currently used criterion (margin discoloration) for replacement of composite resin restorations and explore the effect of alternative treatment strategies. The implication is that extending restoration survival time should conserve tooth structure and significantly decrease restorative dental care delivery costs.